Deep fryers are commercially used by restaurants, institutional kitchens, and fast food establishments for cooking a variety of food products, such as french fries, fish, fried chicken, and the like. The fryer must not only accommodate the individual heating requirements of each particular food product, but it must also maintain consistency and uniformity of taste and texture during the cooking process. The food product is cooked by totally immersing it within a vat or tank that is filled with heated oil or shortening. The oil may be heated using a flow of heated gas that is forced or drawn through flow passages that are located within or external to the cooking vat. A gas burner is provided to heat the gas circulating within the heat exchanger. The oil may instead be heated with an electric heating element disposed in the oil. Examples of other gas burner and electric prior art systems are shown in a report by Pacific Gas & Electric entitled "Development and Application of a Uniform Testing Procedure for Open, Deep-Fat Fryers," dated October 1991.
When cold product for cooking is dropped into the vat, the temperature of the shortening drops. The heating mechanism then tries to reheat the shortening. At times, the cooking loads and temperatures are such that the cooking cycle is completed and the cooked product removed before the fryer can return to its original (pre-drop) setpoint temperature. After the product is removed, the fryer returns to its setpoint temperature. The period of time from when the product is removed until the time at which the fryer returns to it setpoint temperature is known as the recovery time. The fryer is not available for proper cooking during the recovery time. Any food dropped into the vat before the setpoint is reached may be inferior in texture, taste or temperature. Additionally, the product that had previously been dropped into the vat, and caused the drop in temperature of the shortening, may not have had the ideal cooking conditions during its cooking cycle and may, therefore, suffer some degradation in quality.
One attempt at a solution to this problem is what is known as flextime, wherein the actual temperature of the shortening is compared to the ideal temperature, and the cooking time is extended to accomplish the same heat transfer to the food product. This approach, however, does not assure proper texture or taste as the cooking often depends on having the right temperature at the right time rather than having some compensated time to account for a variance in temperature.
Electric flyers have been found to return to setpoint temperature in a shorter time than gas fryers of the same power input rating. Electric fryers, however, are more expensive to operate than gas fryers due to the higher cost of electric energy. Additionally, the quickness of an electric fryer is not needed at all times, for example, during warm-up and idling periods, and for certain light cooking loads.
It is an object of the present invention to provide a boost heater for a deep fryer which reduces or wholly overcomes some or all of the aforesaid difficulties inherent in prior known devices. Particular objects and advantages of the invention will be apparent to those skilled in the art, that is, those who are knowledgeable or experienced in this field of technology, in view of the following disclosure of the invention and detailed description of certain preferred embodiments.